Genotypes of rapeseed with wide adaptation in contrasting environments of the Argentine Pampa

MIRALLES D.J; RONDANINI D; PUHL L; IRIARTE ; LOPEZ CESAR

Berlin

Congreso; 15 International Rapeseed Congress,; 2019

Oilseed rape grain yield has increased in the last 40 years in most countries, but this yield gain has not been accompanied by greater yield stability. This study was aimed to (i) quantify the genotype by environment (GxE) interaction on oilseed rape yield, to identify (ii) genotypes with broad adaptability, and (iii) thethe main environmental drivers related to grain yield, by applying a linear mixed model to official multi?environment trials (MET) of 9 spring genotypes (G), in 3 locations (L) during 6 years (Y) on central and southern Argentine Pampas (31 to 38 º S latitude) under rainfed conditions. The database contained 9 commercial spring genotypes (coded as G1?G9), including 3 hybrids and 6 open?pollinated genotypes (released from 1997 to 2010), sown along an optimum range of sowing dates (May-June)between over 2007 and ?22012 growing seasons. Locations contrasted in soil and climate characteristics. Weather conditions were highly variable among years, with 2007 as the coolest and 2008 as the warmest year. There was a 4?fold rainfall variation between years, with 2008 and 2012 as the driest and wettestyear, respectively. Also, the number of days with frostsshowed important variations between years and locations. Best linear unbiased prediction (BLUP) of grain yield ranged 500-3600 kg/ha. The adjusted linear mixed model explained 86 % of total variability. Fixed effectL x Ywas highly significant (P< 0.0001). G variability was estimated as 147 kg/ha of standard deviation. Contrasting genotypes were identified by Shukla?s stability index, and two of them showed the best yield performance in the wettest year. Factor analysis (FA) explained 71% of total variation and discriminated genotypes with broad and specific adaptability, as well as combined environments according to similarities in grain yield of the evaluated genotypes. Environmental loadings of Factor 2 (20.5%) were associated with cumulative rainfall in the post-flowering period(up to 230 mm). Itis wasconcluded that (i) a significant G x L x Y interaction underlies the high variability of grain yield, (ii) genotypes (G6 and G7) with high yield stability were identified, and (iii) GxE effects are associated with post-flowering rainfall in Argentine Pampas.